Apparently the British dvd is now out of print/hard to find, so you will not find it in shops except online from independent sellers on things like ebay/amazon.
If you want it brand new from sellers it's going to cost more. I wouldn't pay £19+ for it...
If you have a multi region dvd player, it's avaliable on region 1 much cheaper on the American version of Amazon.
Nowadays, I have no idea why anyone in Britain wouldn't have a dvd player that can play ALL dvd regions...
I don't believe it's out anywhere in the world on blu ray yet?
Its not the greatest of the series, but I think the problem with the film is more than just being bac but it was bizarre. It was so totally off the charts, I enjoyed it more looking at it from the perspective of a stand-alone film rather than part of the seriers. As part of the series, well, lets just say there is a lot to complain about.